Telephone



Jan.

J J. SWAN TELEPHONE Filed" Jan. 15, L925 2 Sheets-Sheet 'ill:

/ NVENTOR S. ATTORNEY Jan; 29, 1929.

J. J. SWAN TELEPHONE Filed Jan. 15, 1925 2 SheetsSheet 2 I m a I u a.

EEEEE NVENTOR M; ATTORNEY Patented Jan. 29,1929.

UNITED STATES PATENT .iomr .1. swan, or Mormonism, New JERSEY.

OFFICE.

TELEPHONE.

Application filed January My invention. relates more particularly to a novel method and means by which the sound waves in a telephone may be confined within the transmitter and its stand, and prevented from being propagated outside of the tele-.'

phone, either directly or by reflection from the diaphragm or the inner wall. of the mouthpiece, thus enabling the telephone to be used without the speaker being heard by,

or disturbing, others who may be in his immediate vicinity. L

One object of the invention is to accomplish the'above result in a practical, workable and positive manner without the'use of extraneous or exterior attachments of any sort fastened to or hung upon'or from the telephone mouthpiece, or the body of the transmitter or the stand. H A further object is to efiect silent, or practically silent transmission of sounds and of r the voice, without substantial modlfication of the general form and dimensions or general appearance of the standard telephone transmitter and stand.

A further object is to .provide means for such secret or ractically silent'or disguised transmission of the voice without requiring the speaker to use an instrument that is heavy; awkward, topheavy or different in action or general appearance from that to which he is accustomed. s

A further object is to provide a type of telephone which can be used in the open in ofiices, public places or, in general, in close proximlty to other telephone instruments, or'

to. persons, without causing disturbing noises and'without others being able to understand what the speaker is saying, and without the use of telephone booths.

A; still further object of the invention is to accomplish the desired results without material modification of any fundamental part of the transmitting or wiring or switching elements of the standard telephone, or the 4.? addition of any elements. that will interfere with the normal functioning of the operating parts of thetelephone, or involving'substantial changes in design, materials,.manu- Y factu're or use of the telephone or any change so in its method of installation and use or ob-y jectionable effect on the general service.

The invention will be understood by ref erence to the accompanying drawings in which Fi 1 is a central vertical section 5-: through the transmitter and its stand; Fig. 2 avertical transverse section on the -plane 15, 1925. Serial No. 2,507.

of the line 22 of Fi section on the plane 0 the line 3-3 of-Fig. 1; Fig. 4 a partial section on the planeof the line H of Fig. 1; Fig. 5 a horizontal section on the plane of the line 5-5 of Fig. 1; Fig. 6. a sectional detail of the edge of the base; Fi 7 a horizontal section on-the plane of the line 77 of Fig. 1; Fig. 8 a view partly in vertical section and part elevation of the upper and hinge portion of stand of Fig. 1; Figs. 9, 10, 11 are part vertical mid sections of modifications of'the transmitter; igs. 12 and 13 are perspective views of the diaphragmspf Figs. 10 and 11 respectively; Fig. 14 a vertical mid-section of a modification of the base and Fig, 15 a vertical midsection of a further modification of the transmitter. Similar reference numerals indicate similar parts in the several views.

Referring to 'the drawings the numeral 1 designates the casing of the transmitter Within which is supported diaphragm 2 and carbon particle container 3 which is attached to a bracket piece .3. These parts are ofthe usual and well known construction. The front cover cap 4 is fitted snugly within the casing 1, and'to the front is secured a mouthpiece 5. This is preferably of molded material and is little longer than the usual or standard type, being formed with side extensions 5 to permit the outer edge to completely envelope the lips of the speaker and to'be tightly closed against the face of the speaker without interfering with the movements of the lips necessary for perfect articulation.

My invention is susceptible of-embodiment in various forms capable -of producing the desired result, and those-forms which are described herein arenot to be taken as excluding others which may be found suitable. One form is illustrated in Fig. 1 wherein the cover cap 4 is formed with an inner wall in which are formed two series of openings or ports 6 and 7, asshown in Fig. 2, the former being in front of the diaphragm and the latter near I the periphery of the cover exterior to the diaphragm. The two sets of municate with the-chamber. 8 in the cover, formed by the outer and inner walls, thus providing a continuous or open passageway from the mouthpiece and chamber in front of the diaphragm to the chamber 9 in the case at the rear of the diaphragm, as indicated by the'continuous dotted arrows. The mouthpiece 5 as above stated, is of such de- 1; Fig. 3 avertical ports 6 and 7 com sign and construction as to permit the outer.

edge to be completely sealed against the face of the speaker, when desired, as indicated in- Fig, 1, thus irfsuring all of the sound produced by'the speaker entering and being confined within the mouthpiece and caused to act upon the diaphragm, .and'then to be carried to the rear of the, diaphragm, as will be later described. I

In the standard form of transmitter now in use, the transmitter case is so mounted as to permit of vertical adjustment both up and down. The construction, however, provides an opening to the atmosphere, immediately below the hinge, which permits the passage of the conductors to the transmitter. In the carrying out of my invention which necessitates confining the air pulsations and sound waves within the stand, I have modified the present standard construction as follows:

The top section 10 of the'stand, as shown in Figs. 1, 3 and 8, is formed at its upper end as a hollow clevis or Yhaving openings 10 on its inner bearing faces corresponding with openings in the hinge end 11 of the case 1.- A

pivot pm 12 passes through the center of the hinge with bearings in the clevis and in the v hinge end of the case. The openings 10*- in the upper part of the top section 10 and the hinge end of the casing communicate directly with the chamber 9 in the case at the rear of the diaphragm, the inner faces of the clevis and the hinge end of the case forming a sealed joint with no opening to the atmosphere whatever, as in the standard construction. No obstruction, however, is offered to the passage of the conductors 13,.fro1n the switch terminals and strap sections 14 and 15, to the transmitter.

The lower end of the section lOis supported and sealed in any suitable way in the main tube 16 of the stand, the latter in turn being supported upon the 'baseshell 17 by.

means of a screw collar 18 according to standard practice. As shown in Figs. '1, 5 and 8, the strap opening in the bottom plate 20 of the base eittends a screw 21 which engages the flange 22 at the lower end of the strap, 1%. By tighten ing screw 21 the shoulder 10 ofsection 10 is clamped securely against the upper edge of the tube 16, thus securely locking-together and sealing the sectionlO, tube 16, and the base plate 20, and thereby constituting a continuous closed chamber or passagefrom-the mouthpiece to the base without interference dica-ted by the arrows in Figs. 1 and space provided 14 is se'curedby screws 19 to the lower portion of sectionlO. Through the the upturned flanged edge. of the base plate 20, and also openings 23 in the ring 24 which is used to clamp and hold in place the felt bottom cover 25. Ring 24 also constitutes a 4 guide for thebase shell 17.

stand to, the base and out through the open ings in the outer periphery of the base, as shown by continuous dotted arrows,

tightly against the mouthpiece and breathing or speaking freely and in normal manner into the telephone without interference with articulation, breathing or the normal operathus making possible the speaker closing his face tion of the transmitter, or the switching and other mechanism within the telephone, which cannot be done in any present forms of telephone transmitters of which I have knowledge.

to pass through the closed space provided by the transmitter case, stand and base as inl it is necessary to the carrying out of my invention that the intensity of the sound waves be so diminished that they cease to be audible, or muflied or deadened within this space after they have acted upon the diaphragm. The desired'muffling or deadeningof the sound waves may be wholly or partially effected by the mere provision of the described closed b the transmitter case, standand base. As, liowever, a given telephone may be used by many different persons the intensity of the sounds is not uniform. To assure the desired result of sound muflling under all conditions of use, I introduce either in the'transmitter case, stand or base, mechanical means which absorb or prevent the transmissionof the sound waves beyond the base. It is not of the essence of my invention where the absorbing or muiiling means is located, provided, such means function after the sound waves have acted upon the diaphragm and are then permitted to propagate in the air confined within the transmitter case and stand until they are muffled or diminished so as to be practically inaudible. Nor isthe form of the mufliing or dampening means of the essence of my invention, as the form may be varied within relatively wide. limits. no simple means is illustrated in the drawings by lining the walls of the case, stand and base with felt, cloth, rubber, or any fibrous or other material substantially impervious to sound transmission. This lining is indicated by the numeral 26 in the several drawings. To still further insure, if

While the air pulsations are thus permitted of other sorts.

all be used in 7 up of pressure,

necessary, the mufliing or silencing of the sound waves I may, as indicated in Figs. 1 and 7 introduce partitions 27 and 28 formed of felt, or any other pervious'material permitting the passage of air, but impervious or deadening to sound waves. These partitions ma be conveniently formed as concentric cylinders, labyrinths, spirals or convolutions There may be any desired number, two being illustrated. These parti tions, as shown in Figs.

may be covered with a felt or other air-pervious but sound-absorbing material 30. Also, if desired, an additional air-pervious sheet or disk may be introduced between the 'ianged plate 29 and the base plate'20. Although I have shown these air-pervious but sound-deadening 7 cylinders, linings and disks, it is not absolutely essential to the sucof my invention that they the exact form or manner cessful operation shown, it being obvious that these parts may be variouslyarranged and disposed within the chamber leading from the mouthpiece to the base. I have illustrated one modification the sound absorbing or of the disposition of deadening means in Fig.9 in which the cover of the transmitter is provided structurally with a separate cap 31 extending forward and providing a larger chamber-in front of the diaphragm than that illustrated, in Fig. 1. In this chamber material, sponge rubber, or layers of material pervious'to air and deadening to sound waves, vanes or a labyrinth construction causing the sound waves to travel some distance before being released into the chamber 9 at the rear of the diaphra m, and the continuous passage formed by t e stand and base, as heretofore described. 4

Still another form of sound deadening means is illustrated in Fig. 14, which may be used either a one or in combinationwith the other means described and consists, as

shown, of a mass of sponge/rubber, or a. 33, substantially solid but fibrous material pervious to air, permitting the outward passage of air pulsationsto prevent the building and cause the/deadening of the sound waves and also conversely permit the inhalation of air if the speaker is breathingwith themouthpiece close to the face.

To completely seal the base except for the openings 23 the opening for the incoming wires 34 is sealed by a bushing 35, or other means. i I e Instead of providing escape ports 6 and 7 in the cap 4 for the air pulsations and sound waves, I may make the cap of standard deslgn, as shown in Figs. 10 and 11, and perforate the diaphragm 2* near its peri hery with a series of openings 36, or I may lbcate the erforations 37 in the flange 26 as shown in igs. 11 and 13. In both of these latter 1 and 6, are supported by a perforated flanged plate 29 which is placed soft felt, fibrous 'tion permits the ready forms the air pulsations arid sound wavcs are conducted away continuously as emitted by the speaker without being reflected back into the mouthpiece, in substantially the same way as in the construction illustrated in Figs. 1 and 9. I

In the present standard design of telephone stand the receiver hook extends through a slot in the stand tube 16. In carrying out my invention it is desirable that this slot be closed in order to avoid any opening to the atmosphere through which the sound waves might pass before being muflied. The closure of this slot in tube 16 may be effected in various ways, one means being illustrated in Fig. 8. As there shown, the switch strap 14 is drilled to receive a screw 38 which is tapped into the stop lug 39 of the receiver hook 39. This locks the receiver hook in fixed down position so that it does not function as in the standard telephone when the receiver 40 (shown in dotted lines) is removed,-.the receiver itself, in my construction,;; being utilized to open and close the switch.- In the drawing the receiver is assumed to be removed from the hook, the dotted line merely indicating the position of the receiver when placed on the hook.

WVhen the receiver 40 is on the hook 34' it presses against .the button 41 on. a free moving member 42, the other end of which bears against the regular switch-actuating spring 4 3,causing it to move backward to permit the opening of the spring contacts 15. When the receiver is removed, the spring 43 moves the member 42, thereby permitting the spring to close the contacts 15. 44 is an insulated button'of the usual type'on the inner end of the slot in the standard design of stand. In

order, however, be maintained stand sections, therein may be that the general design may and use be made of existing as far as possible, the slot closed by a plate 45, curved to fit tightly the exterior of tube 16 and to straddle the receiver hook 29. This construcremoval of all of the parts contained with1n the tube 16, just as at present, by removing the screw 21, shown in Figs. 1 and 14. I

From the foregoing description it will be seen that when the user of the telephone desires to carry on a silent conversatiomhe closes the outer-end ofthe mouthpiece by pressing it firmly against his face, as indicated in Fig.1, the design of the mouthpiece being such that when so closed it does not interfere either with the articulation, enun ciati on or breathing of the speaker. When so closed, all oftlie sound waves are confined within and are concentrated, by reason of the P conical shape of the mouthpiece, directly against the diaphragm.

, As the mouthpiece is closed to the atmosphere at its outer end speaker are permitted to continue the sound waves, set in vibration by the theirtravel, after acting upon the diaphragm, through the open ports either in the transmitter cover, or in the diaphragm, into the chamber 9 at the rear of the diaphragm.

relatively 'reater volume than the volume of the ports so that there is effected in such enlarged chamber a partial mufliing or silencing of the sound waves. They then travel directly into and through the narrower passage of the clevis and stand until finally they meet the sound absorbing chamber in the base on a conversation, either speaking himself or listening through tliel'eceiver, he may maintain the position indicated in Fig. 1 without mouthpiece,

. the stand or its base.

" amount and interfering with normal respiration through the nostrils or the mouth. As he speaks into the mouthpiece the air pulsations from the lungs do not build up pressure either in the the transmitter casing 01 the stand, as there is a sufficiently free outlet for the exhaled air from the mouthpiece through the open ports of the casing, the stand and the openings in the base. This enables a substantially balanced air pressure to be maintained on both sides of the diaphragm which does not disturb the normal operation of the diaphragm. The maintenance of this condition involves a proper relation between the cross-sectional areas of the outlet ports leading'from the front to the rear of the diaphragm, and the amount, character and disposition of the sound absorbing material in Such material'is preferlocated in the base asthe latter afiords for its disposition, that is, the arrangement of the sound ab-. sorbing material should be such as to effect the main purpose which is the effectivedeadenmg or muflling of the sound waves, Without preably ample space venting the free escape of the air from the. 50

speakers lungs in order to avoid building up a degree of back pressure of air which would interfere with the free and normal actiop of the diaphragm. a Thus two main factors enter into the practical application of my invention, namely, the

deadening or mufihng of the sound waves within thetransmitter casing and thestand, and the provision of means to prevent the building up of a back pressure at the rear of the diaphragm. .The formerobject is ata tamed by providing a path or conduit for the sound waves other than by reflecting them back from the diaphragm into themouthpiece, that is, by permitting them to bepropagated through the air contained Within the This chamber is of 'ed from the pressure that the user is carrying sound waves so air pressure within the casing and stand is ob viated because the sound deadening means, even if of felt or cloth, is pervious to air in both directions. Should, however, conditions arise in the use of my invention making it desirable to maintain actual atmospheric or exterior air pressure directly on the rear face of the diaphragm entirely independent of and isolator air and sound vibrations in chamber 9, or the pressure and sound in the closed mouthpiece and chamber in front of the diaphragm, I employ a substantial or practically rigid partition 46 to close the recess in the cap or cover/l behind the diaphragm 2. This is sealed aroundits outer edge and is sealed where the fixed portion of the carbon particle container 3 enters through its center portion. In this way 1 form an air tight compartment 47 directly behind the diaphragm. Free access of atmospheric or outside pressure from this chamber is effected by means of a vent hole 4.8 through the cover 4. .Partition 46 may, if desired, serve as the support of part3 thereby making the bracket 3 unnecessary.

While I have shown my invention as applied to the desk type of telephone with separate receiver and stand, it is to be understood that the invention is applicable to other types such as that in which the transmitter and receiver are mounted ona common stand or frame and adapted to be held by the hand against the mouth and ear, and to the automatic pay telephones in which the transmitter case is attached to the front of the coin box. The tei'm sta nd as used by me is therefore to be taken as meaning any form or type of support for the transmitter, and adapted to effect the confining of the sound Waves within-the telephone instrument and the mufiling, neutralizing, absorbing or interference of the sound waves after they have acted upon the diaphragm in the usual or normal manner. In other words,

that there shall be no propagation of such waves through the openings in the transmitter standv which openings are necessary to permit the escape of the air pulto de aden the sations or pumping effects produced by the means to confine and conduct the air pulsations and sound waves around the diaphragm from the front compartment to the rear compartment, and means to prevent accumulated or excessive air pressure inthe rear chamber or passage at the rear of the diaphragm due to the air impulses produced by the speaker.

2. A telephone transmitter comprising a casing having a cap, a diaphragm supported therein, forming front and rear compartments, means to conduct the sound waves that enter the front chamber, after they have acted upon the front of the diaphragm, into and through the second chamber or passage to diminish their intensity so that they cease to.

be audible, or become indistinguishable.

3. A telephone transmitter comprising a casing having a cap, adiaphragm supported within the casing, a mouthpiece attached to the cap and adapted to be closed at its free end by the face of the speaker, and means to cause the air pulsations and sound waves after acting uponthe front of the diaphragm, to be conveyed continuously beyond and away from the rear of the diaphragm, in volume such as to avoid building up of pressure at the rear of the diaphragm to act on the rear or back thereof.

4. A'telephone. transmitter comprising a casing having a cap, a diaphragm supported within the casing, a mouthpiece attached to the cap and adapted to ,be entirely closed at its free end by theface of the speaker, and means for confining the air pulsations and sound waves within the casing and stand, when the free or open end of the mouthpiece is closed by the face of the speaker, and to conduct the air pulsations to escape from the casing and stand in volume suflicient to prevent action on the back of the diaphragm.

5. A telephone transmitter comprising a casing having a diaphragm supported therein, a hollow support for said casing, and means to conduct the propagation of all of the sound waves, after they have acted upon the front of the diaphragm, from the front to the rear of the diaphragm and'through the support, and, a sound muflling device within said support.

6. A telephone transmitter comprising a casin having a cap, a diaphragm supported there y, a mouthpiece attached to the cap and adapted to be entirely closed at its free end by the face of the speaker, means to conduct all the air pulsations and sound waves after acting upon the front of the diaphragm beyond and away from the rear of the diaphragm,

and means to prevent such air impulses and sound vibrations from direct contact with the back of the diaphragm while flowing through the casing.

7. A telephone transmitter comprising a casing having a cap, a diaphragm supported thereby, a partition within the casing at the rear of the diaphragm, said'partition and the diaphragm forming the walls of r" a closed chamber, the casing having a vent from such chamber to the atmosphere, a mouthpiece attached tothe cap adapted to be entirely closed at its free end by the face of the speaker, and means to cause all the air impulses and sound waves after acting upon the front of the diaphragm to be conveyed beyond the diaphragm and chamberclosing partition within the cas-' to cause the air impulses and sound waves after acting upon the diaphragm to be conveyed beyond the diaphragm and chamber closing partition within the casing, without direct action on the rear of the diaphragm.

9. A telephone transmitter comprising a hollow casing having at one end a base and at the other a mouth piece jointed to the casing and forming a continuation of the cavity "thereof, a diaphragm transverse to the casing, the casing having means to conduct air pulsations and sound waves around the diaphragm, said base having openings for the escape of air, and mufilin devices in the casing previous to air to ena le the escape thereof at the openings of the base.

In witness. whereof I have hereunto signed my name.

JOHN J. SWAN. 

